1. Technical Field
The present invention relates to a non-contact temperature measurement, and more particularly, to an apparatus and a method for non-contact temperature measurement capable of contactlessly, easily and efficiently measuring the temperature of and/or the temperature distribution throughout a measurement object.
2. Related Art
There has been a demand in various fields that the temperature of a measurement object be accurately measured. In a semiconductor manufacturing apparatus where a semiconductor wafer is subject to various processes, an accurate temperature management of a wafer is important to permit the apparatus to fully exhibit its performance to attain an improved yield.
For temperature measurement of a semiconductor wafer, apparatuses of contact type and non-contact type are known as disclosed in Japanese provisional patent publication nos. 2000-241257, 6-341905 and 11-248539.
Specifically, a contact-type temperature measuring apparatus is provided with thermocouples that are formed on a semiconductor wafer together with conductive lines and a connector. The thermocouples are connected through the conductive lines and the connector to an extension cable. In measuring the temperature of the wafer, outputs of the thermocouples are supplied to an external measuring instrument through the conductor lines, connector and extension cable.
Thus, the contact-type apparatus requires signal lines corresponding in number to the thermocouples, resulting in a complicated structure. In addition, countermeasures must be taken for preventing extraneous noise from entering into the signal lines to improve the measurement accuracy. In a case where a temperature measurement be made on a rotating semiconductor wafer, a signal cable hinders the wafer from rotating, making it impossible to carry out the measurement.
On the contrary, a non-contact type temperature measuring apparatus is free from problems caused by a signal cable since it is provided with sensors for contactlessly measuring the surface temperature of a semiconductor wafer based on a temperature-dependent thermal emittance or light transmittance of the wafer. However, such an apparatus entails another problem of how to remove the influence of individual differences between semiconductor wafers. Moreover, countermeasures must be taken such as to protect a semiconductor wafer from a thermal source or extraneous light affecting on the measurement accuracy.
To remove a signal cable, still another attempt may be made to use a transmitter for wirelessly transmitting outputs of thermocouples. In such an arrangement, however, difficulties will be encountered in mounting a semiconductor wafer with a transmitter and a battery serving as a drive source thereof. The usage of a battery entails problems such as heat generation and short battery life.